Fix efficiency bug detected by Kieran Elby.

2 files changed, 18 insertions, 2 deletions

diff --git a/ChangeLog b/ChangeLog
index 3e8dc18..558d591 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2008-09-10  Donal K. Fellows  <dkf@users.sf.net>
+
+	* generic/tclListObj.c (Tcl_ListObjGetElements): Make this list->dict
+	transformation - encountered when using [foreach] with dicts - not as
+	expensive as it was before. Spotted by Kieran Elby and reported on
+	tcl-core.
+
 2008-09-08  Donal K. Fellows  <dkf@users.sf.net>
 
 	* tests/append.test, appendComp.test, cmdAH.test: Use the powers of
diff --git a/generic/tclListObj.c b/generic/tclListObj.c
index 7505569..aebaee8 100644
--- a/generic/tclListObj.c
+++ b/generic/tclListObj.c
@@ -10,7 +10,7 @@
  * See the file "license.terms" for information on usage and redistribution of
  * this file, and for a DISCLAIMER OF ALL WARRANTIES.
  *
- * RCS: @(#) $Id: tclListObj.c,v 1.52 2008/08/23 10:54:24 dkf Exp $
+ * RCS: @(#) $Id: tclListObj.c,v 1.53 2008/09/10 13:03:33 dkf Exp $
  */
 
 #include "tclInt.h"
@@ -428,7 +428,16 @@ Tcl_ListObjGetElements(
     if (listPtr->typePtr != &tclListType) {
 	int result, length;
 
-	(void) TclGetStringFromObj(listPtr, &length);
+	/*
+	 * Don't get the string version of a dictionary; that transformation
+	 * is not lossy, but is expensive.
+	 */
+
+	if (listPtr->typePtr == &tclDictType) {
+	    (void) Tcl_DictObjSize(NULL, listPtr, &length);
+	} else {
+	    (void) TclGetStringFromObj(listPtr, &length);
+	}
 	if (!length) {
 	    *objcPtr = 0;
 	    *objvPtr = NULL;